The present invention is directed to a non-light emitting insert for fluorescent lighting fixtures, and more particularly is directed to such an insert used in place of a removed fluorescent lamp from a plural lamp fluorescent lighting apparatus to effect electrical completion of the plural-lamp ballast-type electrical circuit.
With the increased importance being placed on energy conservation, steps have been taken to reduce the lighting levels in many commercial and industrial buildings so as to effect a reduction in the electric power consumed for lighting purposes. Illumination and power levels can be reduced in an incandescent fixture simply by removing alternate incandescent lamps, or by replacing them with lamps of reduced wattage.
On the other hand, for energizing the fluorescent lamps of fluorescent lighting fixtures or other electric discharge lamps in respective lighting fixtures, one or more ballast circuits are necessary to create the required high starting voltages and to limit current after the arc is struck. Moreover, removal of one of the plural lamps from a plural lamp ballast circuit usually will have a detrimental affect on operation of any remaining fluorescent lamps, the operation of the ballast-type electric circuit, or the longevity of any remaining fluorescent lamps and/or the components of the ballast circuit. For example, the remaining lamp may only glow and will not start or the ballast may heat to an undesirably high temperature and/or may over drive the remaining lamp. One reason for such usually encountered detrimental affect is the normally required electrical balance for proper operation of a ballast circuit, which may include transformers, chokes, capacitors, or other electrical components, and such circuits will not operate properly if the electrical balance thereof is radically distorated.
To avoid the above-mentioned and other detrimental affects, one practice that has been followed to reduce light levels and consumed power in commercial and industrial buildings using fluorescent lighting has been completely to extinguish the fixture or at least all the lamps in a respective ballast circuit thereof by removal of those lamps or to deenergize the fixture by rewiring alternate fluorescent lighting fixtures located, for example, along a corridor, in a work area, and so on. One problem experienced when alternate lighting fixtures are extinguished or de-energized is the large unbalanced lighting affect, whereby areas located rather proximate to energized fixtures will be relatively bright but those areas located between energized fixtures and especially located proximate an extinguished fixture will be quite dark. Another drawback to extinguishing alternate fixtures is that the ballast circuit may still draw electric power even though the fluorescent lamps may have been removed from that circuit, therefore unnecessarily wasting electric power, and any rewiring to avoid this waste would be very expensive.
Several types of fluorescent lighting fixtures most commonly used today are the instant start type and rapid start type, and each usually includes a two lamp series sequence ballast circuit. The two lamps operated by one ballast may be in a single plural lamp fixture or in plural single lamp strip lights, for example. An instant start lamp has two single pin electrical terminations or bases and a rapid start lamp has a pair of pins coupled across a cathode heater at each of its bases. Various types of high output fluorescent lamps have special recessed double contact bases or terminations. The electrical properties of a fluorescent lamp are such that it exhibits a high resistance or impedance at starting and a much lower resistance or impedance after the arc is struck and current flows through the lamp, and the energizing ballast circuits are designed with respect to those properties. A principal difference between a conventional two lamp instant start ballast circuit and a two lamp rapid start ballast circuit is that the former does not provide for cathode heating after the arc is struck but the latter includes circuitry for continuous heating of the lamp cathodes.